Kouzmanoff hit a solo home run and singled in another run. Jody Gerut singled in the other Padres' run.
Peavy (3-5) pitched the seventh complete game of his big-league career, striking out eight batters.
Chris Dickerson smacked a solo homer for the Reds.
Bronson Arroyo (5-3) was the losing pitcher, allowing three runs and six hits before leaving in the eighth inning.
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